Radon mitigation in blocks of flats

High concentrations are commonly detected in ground floor flats with the floor in direct contact with the ground. Radon-bearing air can access higher floors through pipe ducts, but such findings are not very common.

In blocks of flats, the best radon mitigation results have been achieved with sub-slab suction and radon well. The breaking of structures in a block of flats is expensive; therefore, sub-slab suction is implemented from the outside through the footing. Underpressure levels in flats are often so high that it complicates the functioning of the extractor fan and the well. Installation of fresh air ventilators can improve the result of mitigation measures.

Installation of fresh air ventilators can reduce the underpressure in the flat and the radon flow from the soil. Furthermore, the sealing of leakage routes reduces radon flow. However, it is difficult to completely seal all leaks. The installation of fresh air ventilators and sealing of leaks usually reduces the radon concentration by less than 50 per cent. Therefore, usually the best solution is to start planning sub-slab suction or a radon well. Their efficiency can still be improved by installing fresh air ventilators and by sealing.

Radiation and Nuclear Safety Authority (STUK) supervises radiation and nuclear safety in Finland. The purpose of STUK is to protect people, society, the environment and future generations from the detrimental effects of radiation.